Burger King is giving away a voucher for half-price adult entry to a range of UK theme parks with the purchase of any meal between March 22 and October 31, 2010. The vouchers are valid at Alton Towers, Chessington World of Adventures, Thorpe Park, and Legoland Windsor along with a number of other UK attractions operated by Merlin Entertainments Group.

The offer is a particularly good one for groups with an odd number of guests, who are unable to take full advantage of the current spate of 2-for-1 offers for UK parks. Meals at Burger King are priced at around £4.29 and above, but the potential saving at Alton Towers versus buying a ticket online is around £11.40.

The vouchers are valid through most of the 2010 season, but there are some block-out dates on which they can't be used:

• Alton Towers - Valid until October 31, 2010. Block-out dates: May 23, June 27, 2010.
• Thorpe Park - Valid until November 7, 2010. Block-out dates: October 23-31, 2010.
• Chessington World of Adventures - Valid until November 1, 2010. Block-out dates: all Zoo Days
• Legoland Windsor - Valid until November 7, 2010. Block-out dates: None (note that the park is closed on some days during the season).